Inflammation is often induced by proinflammatory cytokines, such as tumor necrosis factor (TNF), interleukin (IL)-1α, IL-1β, IL-6, platelet-activating factor (PAF), macrophage migration inhibitory factor (MIF), and other compounds. These proinflammatory cytokines are produced by several different cell types, most importantly immune cells (for example, monocytes, macrophages and neutrophils), but also non-immune cells such as fibroblasts, osteoblasts, smooth muscle cells, epithelial cells, and neurons. These proinflammatory cytokines contribute to various disorders during the early stages of an inflammatory cytokine cascade.
Inflammatory cytokine cascades contribute to deleterious characteristics, including inflammation and apoptosis, of numerous disorders. Included are chronic and acute disorders characterized by both localized and systemic reactions, including, without limitation, diseases involving the gastrointestinal tract and associated tissues (such as appendicitis, peptic, gastric and duodenal ulcers, peritonitis, pancreatitis, ulcerative, pseudomembranous, acute and ischemic colitis, diverticulitis, epiglottitis, achalasia, cholangitis, cholecystitis, coeliac disease, hepatitis, Crohn's disease, enteritis, and Whipple's disease); systemic or local inflammatory diseases and conditions (such as asthma, allergy, anaphylactic shock, immune complex disease, organ ischemia, reperfusion injury, organ necrosis, hay fever, sepsis, septicemia, endotoxic shock, cachexia, hyperpyrexia, eosinophilic granuloma, granulomatosis, and sarcoidosis); diseases involving the urogenital system and associated tissues (such as septic abortion, epididymitis, vaginitis, prostatitis, and urethritis); diseases involving the respiratory system and associated tissues (such as bronchitis, emphysema, rhinitis, cystic fibrosis, pneumonitis, COPD, adult respiratory distress syndrome, pneumoultramicroscopicsilico-volcanoconiosis, alvealitis, bronchiolitis, pharyngitis, pleurisy, and sinusitis); diseases arising from infection by various viruses (such as influenza, respiratory syncytial virus, HIV, hepatitis B virus, hepatitis C virus and herpes), bacteria (such as disseminated bacteremia, Dengue fever), fungi (such as candidiasis) and protozoal and multicellular parasites (such as malaria, filariasis, amebiasis, and hydatid cysts); dermatological diseases and conditions of the skin (such as psoriasis, burns, dermatitis, dermatomyositis, sunburn, urticaria warts, and wheals); diseases involving the cardiovascular system and associated tissues (such as vasulitis, angiitis, endocarditis, arteritis, atherosclerosis, thrombophlebitis, pericarditis, congestive heart failure, myocarditis, myocardial ischemia, periarteritis nodosa, restenosis and rheumatic fever); diseases involving the central or peripheral nervous system and associated tissues (such as Alzheimer's disease, meningitis, encephalitis, multiple sclerosis, cerebral infarction, cerebral embolism, Guillame-Barre syndrome, neuritis, neuralgia, spinal cord injury, paralysis, and uveitis); diseases of the bones, joints, muscles and connective tissues (such as the various arthritides and arthralgias, osteomyelitis, fasciitis, Paget's disease, gout, periodontal disease, rheumatoid arthritis, and synovitis); other autoimmune and inflammatory disorders (such as myasthenia gravis, thryoiditis, systemic lupus erythematosus, Goodpasture's syndrome, Behcets's syndrome, allograft rejection, graft-versus-host disease, Type I diabetes, ankylosing spondylitis, Berger's disease, and Retier's syndrome); as well as various cancers, tumors and proliferative disorders (such as Hodgkins disease); and, in any case the inflammatory or immune host response to any primary disease.
The early proinflammatory cytokines (e.g., TNF, IL-1, etc.) mediate inflammation, and induce the late release of high mobility group protein 1 (HMG1) (also known as HMG-1, HMG1, and HMGB1), a protein that accumulates in serum and mediates delayed lethality and further induction of early proinflammatory cytokines.
HMG1 was first identified as the founding member of a family of DNA-binding proteins termed high mobility group (HMG) that are critical for DNA structure and stability. It was identified nearly 40 years ago as a ubiquitously expressed nuclear protein that binds double-stranded DNA without sequence specificity.
HMG1 binding bends DNA to promote formation and stability of nucleoprotein complexes that facilitates gene transcription of, for example, glucocorticoid receptors and RAG recombinase. The HMG1 molecule has three domains: two DNA binding motifs termed HMG A and HMG B boxes, and an acidic carboxyl terminus. The two HMG boxes are highly conserved 80 amino acid, L-shaped domains. HMG boxes are also expressed in other transcription factors including the RNA polymerase I transcription factor human upstream-binding factor and lymphoid-specific factor.
Recently, it has been found that the HMG A box serves as a competitive inhibitor of HMG proinflammatory action, and the HMG B box has the predominant proinflammatory activity of HMG (See, e.g., US20040005316). HMG1 has been demonstrated to be a long-searched-for nuclear danger signal passively released by necrotic, as opposed to apoptotic cells that will induce inflammation. It has also been shown that HMG1 can be actively secreted by stimulated macrophages or monocytes in a process requiring acetylation of the molecule, which enables translocation from the nucleus to secretory lysosomes and results in the secretion of an acetylated form of HMG1. See, PCT/IB2003/005718. Thus, HMG1 passively released from necrotic cells and HMGB1 actively secreted by inflammatory cells are molecularly different.
Further, HMG1 has been implicated as a cytokine mediator of delayed lethality in endotoxernia. See, e.g., U.S. Pat. Nos. 6,468,533 and 6,448,223. More specifically, it is been demonstrated that bacterial endotoxin (lipopolysaccharide (LPS)) activates monocytes/macrophages to release HMG1 as a late response to activation, resulting in elevated serum HMG1 levels that are toxic. Antibodies against HMG1 have been shown to prevent lethality of endotoxin even when antibody administration is delayed until after the early cytokine response. Like other proinflammatory cytokines, HMG1 is a potent activator of monocytes. Intratracheal application of HMG1 causes acute lung injury, and anti-HMG1 antibodies protect against endotoxin-induced lung edema. In addition, serum HMG1 levels are elevated in critically ill patients with sepsis or hemorrhagic shock, and levels are significantly higher in non-survivors as compared to survivors.
Extracellular HMG1 acts as a potent mediator of the inflammatory cascade by signaling via the Receptor for Advanced Glycated End-products (RAGE) and via members of the Toll-like receptor (TLR) family. See, e.g., U.S. patent publication no. US20040053841.
High mobility group protein 2 (HMG2) (also known as HMGB2 and HMG-2) is a close relative of HMG1 that likely originated from gene duplication. It is present in many cell types and shares many if not all of the biochemical properties of HMG1 (Bustin, 1999, Mol. Cell. Biol. 19, 5237-46 and Thomas et al., 2001, Trends Biochem. Sci. 26, 167-74). Although HMG2 is less abundant and has a more restricted distribution than HMG1 in adult mouse tissues, it is relatively abundant in the lymphoid organs, testis and lung where it may also play a role as a mediator of inflammation. Like HMG1, HMG2 is also a significant target antigen of autoantibodics (e.g., perinuclear anti-neutrophil cytoplasmic antibodies) in a number of autoimmune diseases including, systemic rheumatic diseases (Uesugi et al., 1998, J Rheumatol. 25:703-9), ulcerative colitis (Sobajima et al., 1998, Clin Exp Immunol. 111:402-7) and juvenile idiopathic arthritis (Wittemann et al., 1990, Arthritis Rheum. 33:1378-83; Rosenberg et al., 2000, J Rheumatol. 27, 2489-93).
Given the fact that antibodies that bind to HMG1 and polypeptide fragments thereof (e.g., HMG A and HMG B box) have been shown modulate the activity of HMG1 (e.g., proinflammatory activity), and the fact that modulating HMG1 activity in humans may have profound therapeutic uses for many diseases and disorders, there is a need in the art to identify antibodies that specifically bind HMG1 and polypeptide fragments thereof that have high affinity for HMG1 and low immunogenicity. Similarly, molecules that modulate the activity of HMG2 (e.g., antibodies that specifically bind HMG2 and polypeptide fragments) may also be useful therapeutics for a number of diseases and disorders.